Enable I2C on the Atlas Scientific EZO circuits

Manually switch each of your EZO circuits to I2C. Step-by-step tutorial for this is here. TL;DR Use your breadboard, a 5V DC power supply and some jumper wires to short PGND and TX before powering the circuit with 5V. Each power cycle with shorted PGND/TX will switch from UART to I2C and back.

Connect the Tentacle Mini and the Raspberry Pi

Pins to connect are 5V, IOREF, GND, SDA, SCL. In case you don’t intend to use your Tentacle Mini with an Arduino at all, you should consider ordering the Kit version. It comes without the Arduino headers pre-soldered and you can mount your own custom connector just for the required pins.

Tentacle 5V -> RPi 5V
(used to power the 2 isolated power circuits on the Tentacle)

Tentacle IOREF -> RPi 3.3V
(used to power the isolated I2C communications – the Pi wants 3.3V on the I/O, so we apply 3.3V)

In this example, a pH and a DO circuit are plugged in. Te factory settings for the EZO circuits are as follows:

DO: 0x60 (97)

ORP: 0x61 (98)

pH: 0x63 (99)

EC: 0x64 (100)

RTD: 0x66 (102)

If you’re using multiple of the same type of EZO circuit (e.g. 2x pH), both will have the address 0x63. I2C must be unique. You’ll want to connect only one of the circuits at first and change it’s address. You can do this in the interactive example code below by typing i2c,105. This will give this circuit the address of 0x69 (105). You can now plug in the next circuit of the same type.

The following code is provided by Atlas Scientific. You can download it here.